Developing a Custom Farmers Screen Project
Custom Farmers Screens are typically designed for larger projects (greater than 15 CFS screened flow) or for sites where access is not an issue and a concrete structure is preferred. Custom Farmers Screens are always designed in partnership with an engineering firm. FCA provides the design of the fish screen, including the size and shape of the concrete structure that will house the screen components. The engineering firm is responsible for the structural engineering for the concrete structure, as well as the entrance and exit from the screen structure and any additional project components. FCA provides the steel screen components and is responsible for installing the screen components into the concrete structure. FCA will provide the engineering firm with the boundary conditions necessary for the screen to function properly. The engineering firm will be responsible for analyzing the hydraulic conditions of the entire project to ensure proper entrance and exit conditions of the final design.
- Gather initial information about the project. This includes high and low water diversion rates, stream flow information, existing site conditions, and project proponent goals. This can be gathered by FCA, an engineering firm, or any other project developer.
- Perform site visit and conduct survey. The site visit includes verifying any previously gathered information, interviewing operators, land owners, and field biologists as well as conducting a survey of the site. Again, this step can be performed by FCA, an engineer, or any other project developer. A full topographic survey of the site is necessary.
- Analyze project information with particular emphasis on available stream flow in relation to desired screened flow. Using the survey data, analyze the hydraulic grade line in both the stream and the diversion. Head loss through the entrance flume and screen structure must be accounted for to ensure adequate head exists to allow for the screen installation and the associated by-pass/fish return structure.
- Develop final project design and implementation plan. Include input from all project partners and ensure project goals and objectives will be met. Again, ensure all project information is accurate and expectations are realistic.
- Apply for and obtain all necessary permits and approvals.
- Hire contractors for the excavation and concrete work. Ensure that the contractors hired have experience working in and around rivers and streams.
- For a custom Farmers Screen installation, plan on 2 weeks to 3 months for construction depending on the size and complexity of the project.
- Ensure that all project components are placed at the design elevation and location on the site. It is essential to have an experienced project manager or construction engineer on site during all construction activities. Improper elevations will lead to a screen project that does not perform as designed.
- Once the concrete has adequately cured, installation of the fish screen components can begin. Typically FCA will be responsible for installation of the screen components. Depending on the size of the screen, this will take between one and two weeks.
- Once the screen component installation is complete and all other project components are complete, the screen system can be tested. The screen should be run through the entire expected flow range. Typically, FCA staff will be present for the initial calibration. Minor adjustments to the screen can be made to maximize performance through the entire design flow.
- Perform any planting or site restoration activities necessary to complete the project.
- Conduct any post-project site inspections/visits for project partners, permitting entities, or funders.
- Distribute Farmers Screen operation manuals to project partners that will be operating, inspecting, or helping to maintain the project.
- Provide monitoring forms to project partners who will be visiting the site periodically. Collecting monitoring data will help to identify any operational or design issues that need to be addressed to ensure a successful project.
- Monitor the project at least through the first complete season of operation, and preferably for the first three seasons. It is important to ensure that the project operates as expected through the entire range of flows and conditions.
- If an issue arises with screen performance or operation, contact FCA for input and review prior to making any changes to the screen system.